Method of and apparatus for use in carding staple-length textile fiber



May 29, 1962 P. M. STRANG.

METHOD OF AND APPARATUS FOR USE IN CARDING STAPLE-LENGTH TEXTILE FIBER 2Sheets-Sheet 1 Filed April 2, 1959 INVENTOR. jezer/M 65703 4 BY 4 a A77is May 29, 1962 P. M. STRAN 3,036,343 METHOD OF AND APPARATUS F E INCARDING STAPLE-LENGTH TEX E FIBER 2 Sheets-Sheet 2 Filed April 2, 1959INVENTOR. Peder J1. if/W BY United States Patent 3,036,343 METHOD OF ANDAPPARATUS F011 USE IN CARD- ING STAPLE-LENGTH TEXTHIE FIBER Peter M.Strang, Needham, Mass, assignor to The Whitin Machine Works,Whitinsville, Mass, a corporation of Massachusetts Filed Apr. 2, 1959,Ser. No. 803,737 14 Claims. (Cl. 19104) This invention pertains totextile fiber preparation and more especially to a novel method of andapparatus for use in carding staple-length textile fiber, of whichcotton is hereinafter referred to, but without limitation, as anexample.

Preparatory to spinning fiber into yarn, and especially if the fiber beof natural origin, for instance cotton or Wool, many preliminaryoperations are required in order to insure the production of yarn ofuniform character, in particular such operations as blending or mixingto insure uniformity of length, grade, color, etc.; opening and cleaningto loosen dense lumps of adherent fibers and to facilitate the removalof impurities such, for instance, as parts of the cotton plant, burrs,sand, etc.; and the reduction of the cleaned fiber to the form of acoherent sliver which may be subjected to such operations as drawing,doubling, etc., immediately preceding actual spinning. Among the last ofthese preparatory operations is that of carding whereby the fiber, whichhas already been opened and cleaned to a substantial extent (althoughindividual fibers are still clinging together in the form of tufts andwithout any regular order) is further loosened so as to isolateindividual fibers, so far as may be practical; foreign substances notpreviously eliminated are removed; exceptionally short fibers areseparated as waste; the useful fibers are brought into some degree ofparallelism and are uniformly distributed to form a fleece of eventhickness from edge to edge; and the conversion of this fleece into asliver of uniform weight per yard. Since the early days of machinecarding, the distribution of the fibers to form a substantially uniformfleece of even thickness has been practiced by distributing the fibrousmaterial (as received in bat form from one of the preliminary machines)over the face of a rotating drum covered with projecting teeth usuallyof the form 'known as card clothing and, while rotating this drum slowlyin one direction, engaging the exposed surface of the fibrous fleece,adherent to the teeth on the drum, with a similar toothed surface,either stationary or moving slowly relatively to the drum, the generaltheory of operation apparently having been that the two sets of opposedteeth or pins, one set moving relative to the other exert a combingaction whereby the fibers are loosened so that foreign matter and shortfibers are separated and the staple-length fibers uniformly distributedand, in theory at least, arranged more or less parallel. This commonlyaccepted idea as to the mode of operation of the conventional card wasbased upon results rather than upon careful analysis of the actualoperation and fails to explain such questions as:

(1) Why does the cylinder of a card load during operation? (2) Why doesthe doffer load during operation? (3) Why are accurate settingsnecessary between cylinder and licker-in, cylinder and flats, cylinderand percentage plate, cylinder and doifer and cylinder and underscreens? (4) Why does a cylinder speed of 165 r.p.m. necessarily givethe best results? (5) Why does the centrifugal force of the cylinder notthrow the fibers back on the licker-in or on the flats? 3,936,343Patented May 29, 1962 (6) Why are present types of card clothingsatisfactory? (7) Why does a card operate when its cylinder is coveredwith non-flexible clothing which is similar to the covering of alicker-in? (8) Why does a continuous stripper on a cylinder cause a cardto operate satisfactorily, in some instances, even though it tends todull the wire on the cylinder? It may be noted that as the result ofpractical experience in the mill, and as respects the operation, forexample, of the conventional revolving-flat card, the setting of theflats relatively to the rotating cylindrical drum, as well as theangular velocity of the drum for optimum results, have becomesubstantially standard in the industry.

A recent effort to explain the operation of the conventional card hasapproached the problem from the standpoint of fluid dynamics. The theoryof fluid dynamics establishes that in the flow of fluids about arotating cylinder the velocity of the fluid at the surface of thecylinder equals the velocity of the cylindrical surface itself, and thatwhen fluid flows in a channel the velocity of the fluid at the channelwall is zero, but increases very rapidly from zero to a finite value ina very narrow boundary layer along the channel wall. In considering howthis principle may be involved in the action which takes place in arevolving-flat card, it may first be noted that the cylinder is coveredwith card clothing, the flat or flats being likewise covered with cardclothing, and in common practice so arranged that the ends of the teethof the card clothing on the cylinder are spaced approximately 0.009 inchfrom the tips of the teeth on the fiat and, that the flats may beconsidered as stationary as compared with the very high surface velocityof the cylinder, the flats collectively defining the perimeter of aspace or channel bounding a layer of air which is dragged along by thecylinder as the latter rotates. Because the several filaments of airforming this boundary layer having very different velocities, theoutermost filament, as above noted, having substantially zero velocity,any fibers which are introduced into this boundary layer are subjectedto powerful shearing forces between the adjacent air filament, suchforces acting in general circumferentially of the cylinder. On the otherhand, because of the high rotational velocity of the cylinder, thefibers are likewise subjected to centrifugal force of sub stantialmagnitude, Mathematical calculations based upon the employment of acylinder covered with card clothing having 72,000 points or teeth of 33American gauge wire per square foot, and assuming the customary cylinderspeed of rpm. and assuming that the card is designed to produce tenpounds of carded cotton per hour, appear to show that there are morethan 86,800 cubic inches of air available to act upon each cubic inch offiber to be carded, so that the volume of cotton being carded isextremely small as compared with the volume of air in which powerfulshearing forces are taking place as the cylinder revolves. Thus the cardmay be thought of as a machine for generating a high velocity confinedair stream in which a relatively minute quantity of fibrous material issuspended.

The present invention is designed to take advantage of these fluiddynamic principles and in particular the shearing forces within theboundary layer of air surrounding the cylinder and so as to control theflowing'boundary layer of air surrounding the cylinder as to accentuatesuch shearing forces while guiding the air to follow a course such as toimprove the carding operation with respect to the straightening of thefibers and a decrease in the formation of neps such as usually resultfrom the formation of eddies in a body of air in which fiber isfloating.

example,

In accordance with the novel method of carding, 3C1 cording to thepresent invention, the fiber to be carded is distributed over the teethof a layer of card clothing and acurrent of air is caused to flow alongsaid layer of card clothing and in contact with the fiber carried by thelatter, and at regularly recurring intervals, the velocity and pressureof the air forming said current is first increased and then its pressureand velocity are decreased.

'One' desirable apparatus for use in'the practice of this novel methodcomprises a rotatable cylinder whose periphery is covered with outwardlydirected teeth, a device for distributing the fiber to be carded oversaid teeth, mechanism for rotating the cylinder whereby the airsurrounding the cylinder is entrained by the teeth and constrained toflow as a current about the circumference of the cylinder, and anair-confining barrier, extending about a predetermined arc, at least, ofthe cylinder, the inner surface of said barrier being of a shape suchas, at recurrent intervals, first to increase the pressure and velocityof the air forming said current and then to decrease the pressure andvelocity of saidir- V In the practice of the invention, the outerfilaments of the air current, which are generated by the rotation of thecylinder, are caused, at regularly recurring intervals, throughout apredetermined arc of the circumference of the cylinder, first to moveoutwardly away from the tips of the teeth of the card clothing and thento move inwardly toward the tips of said teeth, with a gradual decreasein velocity and pressure of the air as it so moves outwardly and a moreabrupt increase in velocity and pressure as the air moves inwardlytoward the cylinder, and so confining tion of the drum of a cardingmachine, according to the present invention, illustrating the licker-inside of the apparatus;

FIG. 2. is a fragmentary end elevation, partly in radial section, of theapparatus of FIG. 1, but showing the doifer side of the apparatus;

FIG. 3 is a fragmentary radial section, to much larger scale than FIG.1, showing a portion of the air confining barrier, which cooperates withthe drum, in accordance with a preferred embodiment of the invention;

FIG. 4 is an edge elevation of one of the constituent bars of thebarrier shown in FIG. 3;

FIG. 5 is an end view of a single barrier bar in detail, with smallportions of the adjacent bars, and indicating the path of the tips ofthe teeth of the rotating cylinder with relation to the inner surface ofthe barrier bars;

FIG. 6 is a diagram suggestive of the variation in air velocity betweena fixed smooth surface and a smooth rotating surface;

FIG. 7 is a view similar to FIG. 6, but showing what is believed torepresent the actual variation in velocity in the current of air whichis created between a rotating cylinder covered with card clothing and astationary surface covered with card clothing;

the air current that at the points of high velocity it forms 7 jetssubstantially tangent to the surface of the cylinder.

More specifically, the present invention provides a method and apparatusfor use in carding fibrous material which comprises, first distributingthe material over a surface to which the fibrous material tends tocling, for example, a surface consisting of card clothing,

FIG. 8 is a fragmentary radial section illustrating a barrier of anotherform such as might be employed in the practice of the invention; and aFIG. 9 is a small scale diagrammatic end elevation of so much of acarding machine as is necessary to illustrate one arrangement in whichbarrier means, in accordance with the present invention, is employed inassociation with revolving flats. V

The theory of carding, believed to be involved in the present invention,may be understood by reference to then causing a current of air to flowover said surface always in the same direc- .tion, and so confining saidair current that, as it flows, it

forms recurrent high velocity, high pressure jets substantially parallelto said'surface, while in the intervals between successive jets it movesmore slowly with gradually decreasing pressure. For the practice of thismethod it is preferred to employ a carding machine comprising arotatable cylinder covered with card clothing, but relatively stationarymeans having cooperation with the cylinder, which so constrains the aircurrent generated by the rapidly moving card clothing that the velocityof the air current isalternatively increased and decreased and formsrecurrent high velocity jets directed tangentially of the cylinderwherein the velocity of the air current is at a maximum. e

In the attainment of this desirable object, the present inventioncontemplates substituting for some or all of the customary flats of therevolving-fiat card, a stationary barrier, preferably comprising aseries of rigid bars or the equivalent, thereof embracing a portion ofthe carding cylinder or drum and extending from end to end of the latterso as to define the outer boundary of the layer of air which isentrained by the moving drum. Said barrier (in substitution for thecustomary flats) being designed to provide a series of elongate chambersor channels, each extending longitudinally of the drum and eachgradually increasing in radial depth, beginning at one edge of thechannel to a point of maximum depth and then suddenly decreasing indepth in'a smooth arc to the opposite edge of the channel, the channelsbeing separated by portions of, the barrierwhich are spaced :1 veryshort distance, for

instance a distance of 0.009 inch, from the tips of the FIG. 1 is afragmentary radial section showing a porinvention are illustrated by wayof V FIGS. 6 and 7. Thus, in FIG. 6, the character W designates thefixed wall of a smooth surfaced channel K whose opposite wall W ismoving relatively to the wall W and parallel to the latter and towardthe right, as viewed in FIG. 6. In such an arrangement, according to thetheory of flow of elastic fluids, the filament of air which contacts thewall W will move at the same velocity as the latter, this velocity beingindicated by the arrow A while filaments of air between the walls W andW will have progressively decreasing velocities as indicated by thearrows A A etc., until, at the wall W the air will be of zero velocity,assuming that wall W is stationary. However, in apparatus such as atextile card (FIG. 7), wherein the opposed walls of the channel areformed by card clothing, the relative velocities of the filaments of aircontacting the Wall W (which, for example, may represent a stationarycard fiat having the card clothing 25a) and the wall W (which may be arotating card cylinder having the card clothing 255), the relativevelocities of the filaments of air in contact with the walls W and Wrespectively, may probably be represented by the lengths of the parallellines Z Z etc., it being noted that in this case the velocity isprobably nearly constant for a substantial distance outwardly from theperiphery of the rotating cylinder and increases (as indicated at Z fromzero at the base of the stationary card clothing 25a, with an abruptvelocity gradient between the tips of the teeth of the card clothing onthe flat and the tips of the teeth of the card clothing on the cylinder.The present invention takes advantage of this fact by so controlling theair current, outwardly beyond the ends of the teeth of the card clothingon the cylinder, as to utilize the maximum air sheer at this point tothe best advantage in loosening and straightening the fibers and inbringing them into generally parallel relation.

Referring to FIGS. 1-5 of the drawings, the character L (FIG. 1)indicates generally the conventional licker-in mechanism of a cardingmachine. The lap of fiber to be carded is advanced along the feed apron(21, in usual manner, to the feed roll 22. which delivers it to thetoothed licker-in roll 23 which, in turn, carries it across the gridbars 24 and screen 24a and distributes it over the surface defined bythe tips of the teeth or pins of the card clothing 25, which covers theperipheral surface of the carding cylinder 26 mounted on the shaft 27,which is driven by the usual mechanism (not shown). A customary cylinderspeed of 165 r.p.m. and a cylinder surface speed of the order of 36 feetper second may be cited merely as illustrative of good practice. Thecard clothing may be of any conventional type, for example, that whichhas 72,000 teeth or pins per square foot, the teeth or pins being of No.33 American gauge wire. However, for the practice of the presentinvention, other types of teeth may be employed on the peripheralsurface of the cylinder.

The character D (FIG. 2) indicates, in general, the location of aconventional doffer mechanism which is approximately diametricallyopposite to the licker-in mechanism and which includes, among otherthings, the doffer knife-plate 28; the dolfer cylinder 29; and the cardclothing 30 carried by the latter.

In accordance with the present invention, there is provided, insubstitution for the customary revolving-flats, or in substitution for aportion of the revolving-flats, a device herein for convenience referredto as a barrier and which is indicated generally by the character B inFIGS. 1 and 2. If desired, this barrier may extend (FIG. 1) from a pointjust above the licker-in mechanism (in the direction of motion of thecarding cylinder), upwardly and around the carding cylinder and down toa point just above the dolfing mechanism, as indicated in FIG. 2. On theother hand, this barrier may, if preferred, extend only part of the wayabout the working arc of the carding cylinder, the balance of that areof the carding cylinder (which is located between the licker-in and thedotfer) being occupied by conventional revolving-card mechanism. In thatevent the carrier may extend, as a unit, continuously through apredetermined arc of the cylinder, the remainder of the working arc ofthe cylinder having associated therewith licker-in mechanism, asindicated in FIG. 9, or the barrier may be divided into two segments, Band B one adjacent to the licker in and the other adjacent to thedoifer, and the intervening are occupied by the conventionalrevolvingcard mechanism M. Preferably, in accordance with the presentinvention, this barrier extends, as first suggested, from a pointadjacent to the licker-in to a point adjacent to the dofier.

This barrier extends circumferentially of the carding cylinder with itsinner face generally concentric with the carding cylinder and spaced, atall points, from the surface defined by the tips of the teeth of thecard clothing and is carried by rings 31 (FIGS. 2 and 4), located atopposite ends respectively of the cylinder 26, to which the barrier isconnected by bolts 32 (FIG. 4), the rings being adjustably attached tothe frame of the carding machine by brackets (FIG. 2), comprising parts3-3 and 34 which are relatively adjustable radially of the cylinder.However, other means for supporting the barrier may be employed withinthe scope of the invention.

The barrier may, if desired, be a continuous structure, for example assuggested in FIG. 8, consisting of a unitary arcuate mass of material(indicated at 34, FIG. 8), for instance of molded metal or possiblyother material, for example, one of the synthetic plastics or such aplastic reinforced with appropriate material to form a rigid structure,the inner surface of this elongate arcuate member 34 being shaped toprovide a series of ribs 35 with intervening channels 36, these ribs andchannels extending longitudinally of the carding cylinder andsubstantially from end to end of the latter, although the channelsshould terminate a short distance inwardly from the ends of thecylinder.

While such a unitary barrier may be employed (it being understood thatthis barrier will extend throughout that are of the cylinder at whichthe barrier is to function), it is preferred, for ease in manufacture,as well as for accuracy-in adjustment, to make this barrier as disclosedin detail in FIGS. 3, 4 and 5. In accordance with this preferredprocedure, the barrier consists of 'a series of individual bars 37, 37a,37 b, etc., the several bars being identical in construction and beingmade of any suitable rigid material, for example metal or such othersubstance as may prove to be useful for the purpose. These bars, may bemolded to final shape, if of a material which can be molded, or each barmay initially be substantially rectangular in transverse section and ofa length to extend substantially from one end of the cylinder to theother. Thus each bar may, for example, have the outer flat face 38(FIGS. 3 and 5 the parallel edge faces 39 and 40, and an initially flatface, parallel to the face 38, which, during the process of making thebar, is cut away until only marginal portions 38a and 38b (FIG. 5)remain, these marginal portions being substantially fiat and in the sameplane. However, it is contemplated that, for extreme accuracy, thesemarginal faces 38a and 385 may be curved to be concentric with theperipheral surface of the carding cylinder. Ordinarily, because of thediameter of the barrier, flat surfaces at 38a and 38b sufficientlyapproximate concentricity with the carding cylinder to provide allnecessary accuracy.

The inner face of each bar, between the proximate edges of the faces 38aand 38b, is cut away to provide the longitudinally extending channel36b. Experiment appears to indicate that for optimum results the majorportion of the wall of this channel should be a rectilinear surface 41(FIG. 5), inclining outwardly from the plane of the faces 38a and 38b atan angle of the order of 7, although it is contemplated that this anglemay vary slightly in accordance with the type of material with which themachine is intended to operate.

The wall of the channel also comprises the arcuate portion 42, which isconcave rearwardly, as referred to the direction of rotation of thecylinder and whose center of curvature (indicated at C, FIG. 5) is inthe plane of the marginal faces 38a and 38b and whose radius may, forexample, be of the order of A of an inch. As illustrated in FIG. 5, therectilinear surface 41 is tangent to this arcuate surface 42 at thepoint at which the depth of the channel 36b, measured from the plane ofthe surfaces 38a and 38b, it is at a maximum. In FIG. 5, the position ofone of these bars, in particular the bar 37a, is shown in its relationto the card clothing 25, the latter, for convenience in this view, beingshown as resting upon a support S, the geometrical surface defined col-'lectively by the tips T of the teeth of the card clothing beingindicated by .a broken line and as spaced from the plane of the surfaces380 and 38b. In actual practice, this space may, for example, be of theorder of 0.009 inch. As shown in FIG. 5, where portions of three of thebars are indicated, it will be seen that the proximate edges of thesurface 38b and 38a of the bars 37b and 37a, are substantially incontact and likewise that the edges of the marginal surfaces 38b and 38dof the bars 37a and 37b are substantially in contact, the two abuttingmarginal surfaces at each of these points collectively defining theeffective width (circumferentially of the cylinder) of one of the ribs35 of the barrier device. As illustrated, FIGS. 3, 5 and 8, the width ofthe rib is but a small fraction of the width of the groove or channel,for example, if the width of the channel be two inches, the width of therib may be of the order of seven-thirty-seconds of an inch.

Referring to FIG. 4, it may be noted that the groove or channel 36b inthe bar 370, for example, terminates at a substantial distance from theopposite ends of the bar, a distance of the order of 1% being suggestedby Way of example, since this provides ample space between the end ofthe bar and the end of the channel for the reception of the attachingbolt 32, by means of which the bar is secured to the supporting ring 31,while at the same time closing the channel at its ends.

Each of the lateral edges 30 and 40* of the bar is provided with alongitudinally extending groove 43, preferably substantially midwaybetween the surface 38 and barrier so that the current of air, which isgenerated by the entraining action of the teeth ofthe card clothing asthe cylinder revolves, is confined to the space between the innersurface of the barrier and the outer surface of the base fabric of thecard clothing.

It will be observed that the inner face of the barrier, to wit, thatface which is opposed to the tips of the teeth of the card clothing, issmooth, that is to say, it is devoid of anything corresponding to pointsor pins like those of card clothing, so that the flow of the air currentcreated by the revolving cylinder is not aifected other than by thespecific shape or contour of the inner surface of the barrier and thecard clothing on the cylinder. This barrier is normally stationary(althoughit is contemplated that under some circumstances bars such asthose herein shown as constituting the barrier may be substituted withappropriate housing or encasing means) for the usual flats of therevolving-flat card.

With this arrangement it will be observed that the inner surfaces of theribs 35 of the barrier are-very close to the surface defined by the tipsT of the card clothing; and since these ribs are regularly spaced apart,circumferentially of the cylinder, they produce regularly recurrentrestrictions or orifices such that, in passing these n'bs, the aircurrent is increased in 'velocity so that it passes each rib as a highvelocity, high pressure jet, very thin in a its pressure likewisedecreases. The alternating increase and decrease in velocity andpressurehas been found highly effective in loosening and straighteningthe fibers,

and carding by the employment of this relatively simple arrangementincreases production and produces a sliver which is more than usuallyuniform and having its constituent fibers more nearly parallel than iscustomarily the result of the employmentof conventional cardingmachines.

While certain desirable embodiments of the invention have herein beendisclosed by way of example, it is to be understood that the inventionis broadly inclusive of any and all modifications falling within thescope of the appended claims.

I claim: I

1. ii at method of carding textile fiber by the use of a rotatingcylinder whose peripheral surface is covered with card clothing havingoutwardly directed teeth, which comprises as steps: distributing thefiber to be carded over the teeth of the card clothing, and rotating thecylinder thereby generating a current of air which follows the peripheryof the cylinder, causing the outer filaments at least of said aircurrent, at regularly recurring intervals throughout a predeterminedarcof the circumference of radial direction but extending longitudinally ofthe cylinder, and which is directed substantially tangentially to thesurface defined by the tips 'I of the teeth of the card clothing.Experiment shows that in an arrangement such as herein disclosed,wherein the barrier is substantially air-tight, pressure builds upbetween the bars and cylinder such that the air forming'the jets has avelocity exceeding' that of the surfaces of the cylinder. j On the otherhand, intervening between each adjacent pair of ribs there is one of'thechannels 36b, forming a chamber .offorwardly increasing capacity,radially, in which the jetmay expand and gradually losevelocity until,at the portion of the chamber 36b which is of maximum radial width,there is a zone of relative quiet and low pressure. However, it will benoted that beyond this point of width, the charnber decreases veryrapidly in radial width by reason of the short radius arcuate surface42, so that the outer filaments of air, following the surface 41 are suddenly bent inwardly and ultimately turned into .a direc-. tionsubstantially perpendicular to the geometrical surface defined by thetips of the card clothingteeth, these filaments moving initiallyradially of the card clothing and then suddenly being entrained withthose filam'ent's'of the air stream which have been following the tipsof the teeth and carried into the jet stream in the narrow orificebeneath the rib. Thusthere is a terrific sheering action betweenconstituent filaments of the air. stream which is imposed uponthe fibersuspended in the aifstream, therebytendin'gto' drag the fiber outlongitudinally and to separate each fiber from other, adjacent fibers."Desirably the ribs of the barrier are spaced apart a distancesubstantially exceeding the average staple length of the fibers whichare to be carded, for example, for commercial cotton of a rated one inchstaple and which contains"a substantialnumber of fibers of 1% inchlength, a distance oftwo inches between adjacent ribs has been foundsatisfactory for the purpose,

Because of the small angle between the surface 41 at the wall of thechannel in the bar and the plane defined by the marginal faces 38a and38b, the formation of eddies along the. surface of the. cylinder isreduced to a minimum and, as above noted, as the width of the channelincreases the velocity of the air current'moving "along with thecylinder and through this chamber decreases and the cylinder, first tomove smoothly outwardly and without the formation of eddies away fromthe tips of the teeth of the card clothing While continuing, Withoutinterruption, in the same general direction and then to move abruptlyinwardly toward the tips of said teeth.

I 2. The method according to claim. 1, wherein the filament of air whichmove outwardly away from the cylinder make an angle of approximately 7with a tangent to the surface defined by the tips of the teeth and thenmove inwardly toward said surface in an arcuate path whose center ofcurvature is at said surface.

3. That method of carding fibrous material which comprises as steps:distributing the fibrous material over a surface to which the fibrousmaterial tends to cling, causing a current of air to flow over saidsurface always in the same direction, and so confining and guiding saidair current that it moves in the form of regularly recurrent highvelocity, high pressure jets substantially parallel to said surface and,intermediate successive jets, the outer filaments, at least, of said aircurrent move more slowly, outwardly away from said surface, without theformation of eddies and with gradually decreasing pressure.

4. That method of carding fiber of textile length bythe use of arotating cylinder having a peripheral layer of card clothing whichcomprises as steps: distributing fiber to be carded, in accordance withconventional methods, over the surface defined by the tooth tips of thecard clothing, confining the fiber s0 distributed between the tips ofthe card clothing and a stationary substantially air-tight wallextending about a predetermined portion, at least, of the periphery ofthe cylinder, rotating the cylinder thereby to create a current of airflowing in the space between said card clothing and wall and in thedirection of rotation of the cylinder, and at regularly recurringintervals circumferentially of the cylinder, first so graduallyincreasing the radial thickness of said current as to avoid theformation of eddies and then relatively abruptly decreasing theradialthickness of the air current so that its velocity exceeds that of thesurface of the cylinder.

5. That method of carding fiber of textile length by the use ofarotating cylinder having a peripheral layer of card clothing whichcomprises as steps: distributing the fiber to be carded over the surfacedefined by the tooth tips of the card clothing, confining the fibers sodistributed between the tips of the teeth of the cardclothing and astationary substantially air-tight wall extendingabout a portion, atleast, of the periphery of the cylinder, rotating the cylinder andthereby causing a current of air to flow in the space between said cardclothing and wall and in the direction of rotation of'the cylinder, andat regularly re current intervals widening the air current radially at arate corresponding to an angle of the order of 7 to a tangent.

to the periphery of the cylinder thereby decreasing the pressure butWithout forming eddies and then relatively suddenly reducing the radialwidth of the air current and increasing the pressure by constraining itsouter filaments to move toward the periphery of the cylinder along anarc of a radius of the order of of an inch.

6. In a carding machine of the kind which includes a rotatable cylinderwhose periphery is covered with outwardly directed teeth and including adevice operative to distribute fiber to be carded over said teeth,mechanism for rotating the cylinder whereby the air surrounding thecylinder is entrained by the teeth and constrained to flow as a currentabout the circumference of the cylinder, and an air-confining barrierextending about a predetermined are at least of the cylinder, the innersurface of the barrier comprising a plurality of longitudinallyextending radial, shallow channels spaced apart circumferentially of thecylinder by intervening, relatively narrow ribs, the inner faces of allof said ribs being spaced the same distance from the geometrical surfacedefined by the tips of the teeth whereby at recurrent intervals, firstto increase the pressure and velocity of the air which forms saidcurrent and then to decrease the pressure and velocity of said aircurrent.

7. The combination according to claim 6, wherein the shapes of thechannels and ribs are such that at regularly recurrent intervals thecurrent forms high velocity jets directed tangentially of the surfacedefined by the tips of the teeth, and in the intervals between said jetsflows smoothly and at a relatively low velocity. v

8. In a carding machine of the kind which includes a rotatable cylinderwhose periphery is covered with card clothing having outwardly directedteeth and including means operative to distribute fiber to be cardedover the surface of the card clothing, means for rotating the cylinderwhereby the air surrounding the cylinder is entrained by the teeth ofthe card clothing and constrained to flow as a current about thecircumference of the cylinder, a substantially air-tight barrier whichextends circumferentially of the cylinder throughout a predeterminedpart of the circumference of the latter, said barrier being spaced atall points from the surface defined by the tips of the teeth of the cardclothing, said barrier comprising a plu rality of circumferentiallynarrow, peripherally spaced ribs, each rib extending longitudinally ofthe barrier, the inner faces of the ribs being so spaced from thegeometrical cylindrical surface defined by the tips of the teeth of thecard clothing that the air current in passing said ribs in constrainedto form high velocity jets substantially tangent to said geometricalsurface, the inner surface of the barrier, which intervenes between eachpair of adjacent ribs, being smooth and of a shape to form a channelrelatively wide as compared with the ribs, extending longitudinally ofthe cylinder, and wherein the velocity of the air current,circumferentially of the cylinder, is relatively low as compared withthat at the jets, and where in the inner surfaces of the ribs are smoothand substantially parallel to the geometrical surface defined by thetips of the teeth of the card clothing and are spaced from said surfacea distance of the order of 0.009 inch.

9. In a carding machine of the kind which includes a rotatable cylinderwhose periphery is covered with card clothing having outwardly directedteeth and including means operative to distribute fiber to be cardedover the surface of the card clothing, means for rotating the cylinderwhereby the air surrounding the cylinder is entrained by the teeth ofthe card clothing and constrained to flow as a current about thecircumference of the cylinder, a: substantially air-tight barrier whichextends circumferentially of the cylinder throughout a predeterminedpart of the circumference of the latter, said barrier being spaced atall points from the surface defined by the tips of the teeth of the cardclothing, said barrier comprising a plurality of circumferentiallynarrow, peripherally spaced 10 ribs, each rib extendinglongitudinally-of the barrier, the inner faces of the ribs being sospaced from the geometrical cylindrical surface defined by the tips ofthe teeth of the card clothing that the air current in passing said ribsin constrained to form high velocity jets substantially tangent to saidgeometrical surface, the inner surface of the barrier, which intervenesbetween each pair of adjacent ribs, being smooth and of a shape to forma channel relatively wide as compared with the ribs, extendinglongitudinally of the cylinder, and wherein the velocity of the aircurrent, circumferentially of the cylinder, is relatively low ascompared with that at the jets, and wherein the distance betweensuccessive ribs of the barrier substantially exceed-s the staple-lengthof the fibers to be carded.

10. In a carding machine of the kind which includes a rotatable cylinderwhose periphery is covered with card clothing having outwardly directedteeth and including means operative to distribute fiber to be cardedover the surface of the card clothing, means for rotating the cylinderwhereby the air surrounding the cylinder is entrained by theteeth of thecard clothing and constrained to flow as a current about thecircumference of the cylinder, a substantially air-tight barrier whichextends circumferem tially of the cylinder throughout a predeterminedpart of the circumference of the latter, said barrier being spaced atall points from the surface defined by the tips of the teeth of the cardclothing, said barrier comprising a plurality of circumferentiallynarrow, peripherally spaced ribs, each rib extending longitudinally ofthe barrier, the inner faces of the ribs being so spaced from thegeometrical cylindrical surface defined by the tips of the teeth of thecard clothing that the air current in passing said ribs is constrainedto form high velocity jets substantially tangent to said geometricalsurface, the inner surface of the barrier, which intervenes between eachpair of adjacent ribs, being smooth and of a shape to form a channelrelatively widevas compared with the ribs, extending longitudinally ofthe cylinder, and wherein the velocity of the air current,circumferentially of the cylinder, is relatively low as compared withthat at the jets, and wherein the inner surface of the barrier, betweensuccessive ribs, is smooth and slopes outwardly from one edge of eachchannel at an angle of the order of 7 to a tangent to the geometricalsurface defined by the tips of the teeth of the card clothing and thenextends inwardly to the opposite edge of the channel in an arc of theorder of of an inch, whose center of curvature is in the plane definedby the inner surfaces of successive ribs, whereby the channelintervening between successive ribs is of a maximum depth of the orderof of an inch.

11. A carding machine of the kind which includes a rotatable cylinderwhose periphery is covered with card clothing having outwardly directedteeth and including means operative to distribute fiber to be cardedover the surface of the card clothing, means for rotating the cylinderwhereby the air surrounding the cylinder is entrained by the teeth ofthe card clothing and constrained to fiow as a current about thecircumference of the cylinder, a substantially air-tight barrier whichextends circumferentially of the cylinder throughout a predeterminedpart of the circumference of the latter, said barrier being spaced atall points from the surface defined by the tips of the teeth of the cardclothing, and wherein the barrier comprises a plurality of elongateunitary, imperforate rigid bars, each of said bars being substantiallyrectangular in transverse section, each bar having an outer face,parallel edge faces and an inner face, the latter including marginalportions which lie in a plane parallel to a tangent to the geometricalcylinder formed by the tips of the teeth and which intersect therespective edge faces at right angles, the inner surface of the bar,intermediate said marginal portions, comprising a substantiallyrectilinear smooth face, which inclines outwardly and forwardly from itsintersection with the rear one of said trained by the teeth of the cardclothing and constrained to flow as a current about-the circumference ofthe cylinder, a substantially air-tight barrier which extendscircurnferentially of the cylinder throughout a predetermined part ofthe circumference of the latter, said barrier being spaced at all pointsfrom the surface defined by the tips of the teeth of the card clothing,and wherein the barrier comprises a plurality of elongate rigid bars,each extending substantially from end to end of the cylinder, means foruniting said bars leak-tight with their longitudinal edges in contact,each bar having a surface which is opposed to the geometrical surfacedefined by the tips of the teeth, said surface of the bar comprisingmarginal faces lying in the same plane and a single imperforateintervening portion of a width substantially exceeding the combinedwidth of saidmarginal faces and which defines a channel extendinglongitudinally of the'bar, the wall of the channel being smooth andimperforate and comprising a substantially rectilinear portion and anarcuate portion, the rectilinear portion inclining at an angle of theorder of 7 to the plane defined by said marginal faces, and the arcuateportion being of a radius of curvature of the order of &2 of an inchwith its center of curvature in the aforesaid plane, the rectilinearsurface being tangent to the arcuate surface at the point of maximumradial depth of the channel.

13. The combination according to claim 12, wherein the channel in eachbar extends throughout the major portion of the length of the bar butterminates at a dis- Whose surface is of a character such that fibrousmaterial distributed over said surface is carried along an arcuate pathas the drum revolves, means for delivering fibrous material tortheperipheral surface of the rotating drum, and air-tight barrier meanscooperable with the drum to define a plurality of radially, narroworifices spaced uniformly about a predetermined arc of the circumferenceof the drum, each orifice extending parallel to the axis of the drum andthroughout the major portion of the width of the drum, said barriermeans also defining chambers, each of a maximum radial depth greaterthan the radial depth of an orifice, each chamber intervening betweentwo successive orifices and being of a length, circumferentially of thedrum, substantially exceeding the length, circumferentially of the drum,of one of said orifices, whereby the barrier means, in cooperation withthe rotating drum, confines the air which moves in an arcuate pathfollowing the circumference of the drum so that, in passing eachorifice, the air becomes a high velocity jet directed sub stantiallytangentially of the drum, and wherein each chamber which intervenesbetween two successive orifices gradually increases in radial width fromthe discharge side of an orifice so that the air delivered from saidorifice, is permitted to expand and thus lose velocity in moving throughthe chamber, each chamber decreasing abruptly in radial width adjacentto the receiving side of the next following orifice whereby the velocityof air, in leaving the chamber, is rapidly increased to form a jet.

References Cited in the file of this patent UNITED STATES PATENTS270,715, Whitehead -t. Jan. 16, 1883 462,121 Foss -t. Oct. 27, 1891474,349 I Gibson May 3, 1892 2,879,549 Miller et a1. Mar. 31, 1959

